The present invention relates to a particular system and method for reading audit data from a remote mirrored disk and applying the data to a remote database backup copy. A remote database backup is maintained by (i) transferring a package of audit data from a primary database system to a remote system process; (ii) then writing the audit data to a remote disk; (iii) then applying the audited changes to the remote database backup copy. When a network communication error occurs during the first step (i) involving transferring a package of audit data from a primary database to a remote system process, then, the primary database system activity is temporarily suspended.
This temporary suspension of database activity presents problems and is counter-productive to the goal of maintaining 100% database availability. Thus, in this regard, if a remote database backup could be maintained by reading audit data from a remote mirrored disk, then database availability could be maintained and by not being affected by network communication errors, while at the same time network performance would be improved when the remote mirrored disk is used to off-load network activity.
There are a number of patented prior art technologies which operate in the field of database backup using mirrored disks. These prior art methods can be summarized, as indicated herein below.
The Konrad patent, U.S. Pat. No. 5,404,508 entitled “Database Backup and Recovery System and Method” involves a method for maintaining a backup database. However, while Konrad teaches a limited method to read audit information but only when it is available, Konrad does not teach a method to determine “when” the audit information is available, as is done in the present invention.
The Yanai patent, U.S. Pat. No. 5,742,792 entitled “Remote Data Mirroring” involves two data storage systems interconnected by a datalink for remote mirroring of data. However, while Applicants also uses the concept of “disk mirroring”, Applicants function and purpose is quite different, in that the present system of Applicants reads from a remote mirror for the purpose of maintaining a backup database system.
The Mosher, Jr., patent, U.S. Pat. No. 5,745,753 is entitled “Remote Duplicate Database Facility With Database Replication Support For Online DDL Operations”. This patent involves a remote data duplication facility which maintains virtual synchronization of the backup database with the local database. The Mosher reference teaches a method of managing method buffers at the source host, including waiting for an acknowledgment from the remote host. However, the advanced method described in the present application eliminates the need for any acknowledgment and the managing of message buffers, thus effectively improving system performance at the source host.
Thus, as previously mentioned, the present invention provides a particular system and method for reading audit data from a remote mirrored disk and applying this data to a remote database backup copy. The present invention allows for the maintenance of a remote database backup which can be provided by reading the audit data from a remote mirrored disk, thus, allowing for the maintainability of the database and not being affected by network communication errors.